About Readability Scorer

Flesch + grade-level estimate for any prose block. Part of the DevTools Surf developer suite. Browse more tools in the Text / String collection.

Use Cases

• Ensuring developer documentation is accessible to junior engineers
• Checking that marketing copy matches the target audience's reading level
• Improving API documentation readability for non-native English speakers
• Validating that legal terms of service meet plain-language requirements

Tips

• Aim for a Flesch score of 60-70 for general web content
• Check the grade level to match your target audience
• Rewrite sentences flagged as complex to improve the score

Fun Facts

• The Flesch Reading Ease test was developed by Rudolf Flesch in 1948; the US Department of Defense adopted it in 1978 for all military manuals.
• The average American reads at a 7th-8th grade level, which is why most major newspapers target that readability score.
• Amazon requires Kindle book descriptions to score at least 50 on the Flesch scale, and US insurance policies must score above 40 by law in many states.

FAQ

Which readability formulas does it use?

Flesch Reading Ease, Flesch-Kincaid Grade Level, and the SMOG index. Each gives a slightly different angle on text complexity.

What's a 'good' Flesch score?

60–70 for general audience (plain English), 80+ for kids' content, below 30 for academic papers. For marketing copy aim for 60–70; for technical docs 50–60.

What does the grade level mean?

Years of US school education required to easily read the text. Grade 8 is the recommended target for consumer-facing writing (matches the median adult reading level).

Do the formulas work for non-English?

No — they're calibrated on English syllable patterns and sentence lengths. For other languages, use language-specific metrics (LIX for Nordic, Fernández Huerta for Spanish).